I applaud Christof Koch for looking with fresh eyes into the puzzle of free will in Finding Free Will. He is certainly correct that many of our overt actions are led by brain events we have no awareness of, and this can be a good thing. As William James once remarked, it's a good idea to run from the bear before you have a fully conscious experience of bear. Drop a fragile object, and you react without getting tangled up in thoughtthe latter would be way too slow. But that says little about the will to action or the choice to do this or that freely.

So the points of Koch's article are well taken, and I am delighted that he has both the courage and skills to pursue a topic that is as important as it is confusing.

The paradox, if there is one, is that I feelright nowI am freely writing this. That is my internal response at the moment. Who knows what developmental histories in my life also contributed to this free choice? So scribble I do.

Neuroscientists and psychologists (and others) are becoming more alert to the fact that many of our critical brain decisions are nonconscious ones. The stories we construct come later, and these in themselves may have little to do with the true causal network that has been activated. In our stories we are free. Stories are stories. That may be it. But the phenomenology of sensed freedom is real.

I have no great (if any) insights into this but am delighted that the issues are being explored with the best tools we currently have available. I will not be surprised if, as the result of future analytical efforts, more surprises come down the road. I will be surprised if they don't.

John C. Fentress
Eugene, Ore.commenting at www.ScientificAmerican.com/Mind


Healthy Skepticism, by Sandra Upson, discusses the health and happiness of theists versus atheists in terms of community and like-minded people. Could it be that theists are healthier and happier (at least in part) because religion insulates/isolates the believers from the reality of the world around them? For instance, if you believe that you'll go to heaven, then you might find the unpleasantness of reality less depressingGod is testing you, and you want to pass the test, and this helps you have the strength to overcome the adversities you encounter.

Ted Grinthal
Berkeley Heights, N.J.


The highly interesting article The Subtle Power of Hidden Messages, by Wolfgang Stroebe, failed to discuss one important item: the attitudinal effects of mere exposure, especially in those cases where the stimuli are presented either subliminally or masked by some otherdistractingstimuli.

To take just one of many more experiments: in 2004 Karl Szpunar of Harvard University and his colleagues found that music fragments were evaluated more positively the more they had been presented, at least when the subjects had not been listening to the music in a focused way but just heard it incidentally. Other investigators found similar results with polygons, photographs and other images that were administered subliminally.

Advertising in magazines and show bills in the street may work the same way. It's not necessary that people read the messages. They probably don't even know which panels they have passed on the way to their office. But they may have noticed them incidentally, and so the repeated exposure gradually has been turning their attitude toward the positive. When they need something later on, the more positive attitude toward this particular product or brand name can (in addition to other influences, like the packing color) unconsciously influence the choice they make.

Pol Craeynest
Marke, Belgium


In regard to This is Your Brain on Drugs, by Christof Koch [Consciousness Redux], we are to be surprised that taking hallucinogens results in reduced brain activity. After all, such drugs are called consciousness-expanding and mind-expanding, based, I suppose, on the wow effect one experiences. Yet what are consciousness-expanding and mind-expanding supposed to mean? What actually expands? Wowness? Maybe the surprise is increased by a bad choice of hyperboles in the first place.

George Gillespie
Moorestown, N.J.


The Aviator's Dilemma, by Stephen L. Macknik, Susana Martinez-Conde and Ellis C. Gayles, is a great article! The illusions that pilots experience were well explained. I flew as a passenger in navy P3 planes during the cold war, and it was easy to become somewhat disoriented flying between cloud layers that seem horizontal but aren't always actually horizontal; they form along pressure gradients rather than just altitude.

Not only that, but the relatively slow-moving P3 sometimes feels like it is flying backward after a great many hours of cruising. Not only does one get visual effects, but also auditory effects as one's ears try to make sense of the constant droning of engines and avionics. Sometimes I heard classical musicnot like a replay in my mind, but I could actually hear it amid the droning of the engines. Knowing it was an illusion did not make it go away.

When you drop down to 500 feet above the oft-stormy sea to inspect a ship, you depend almost entirely on the radar altimeter and attitude indicator because there is no horizon, and you have absolutely no idea whether you are too close to little waves or adequately high above really big wavesit all looks the same. Then you finally see the ship and realize the waves are really big, twice the distance crest to crest as a supertanker is long.

commenting at www.ScientificAmerican.com/Mind


In Redefining Mental Illness, Ferris Jabr writes, Although many psychiatrists do not sit down with the DSM and take its scripture literally ...

This is an important caveat. And it illustrates why more attention needs to be drawn not to what's in the book but to how the book is used.

As a practicing psychiatrist, I agree with Jabr that many clinicians rely on personal expertise to make a diagnosis. What we are forced to write in the chart, however, is dictated by the DSM. From that point on, the diagnosisNOT the patientbecomes the focus of treatment. The diagnosis serves as a gateway not only to a wide range of social serviceswhich could be beneficialbut also to a potential lifetime of medication trials and other ill-advised treatments.

Most psychiatrists view the DSM and the diagnostic process as a necessary evil: necessary for reimbursement and to be able to help the people who seek our assistance but evil because in many systems the assistance we provide is dictated by the diagnosis, not by the unique needs of the individual.

commenting at www.Scientific American.com/Mind


I am not sure what is new about Scott O. Lilienfeld and Hal Arkowitz's article When Coping Fails: Revisiting the Role of Trauma in PTSD [Facts and Fictions in Mental Health]. Complex PTSD (C-PTSD), proposed for inclusion in the DSM-V, was described in 1992 by trauma expert Judith Herman in her classic Trauma and Recovery (Basic Books). The notion, in a nutshell, is that various life stressors and events can collectively lead to PTSD-like symptoms and conditions, which may be remediated via treatments used for conventional PTSD, notably EMDR [eye movement desensitization and reprocessing].

Yitzchak Samet
commenting at www.ScientificAmerican.com/Mind